Note: Only complications relevant to the anastomosis are discussed here!
Suture line failure
Common causes for suture line failure include: Liberal skeletonization of the intestinal wall (impaired perfusion), sutures under tension (dehiscence), and intramural hematoma. Irradiation, impaired perfusion, steroid and cytostatic therapy, catabolism, and states of shock are other risk factors in intestinal sutures.
Insufficient physiological fibrin adhesion, infections, and anatomical or microbial features also promote suture line failure. Additional extraluminal reinforcement in intestinal sutures includes coverage with peritoneum and omentum or with absorbable material such as PGS mesh and coating the anastomosis with fibrin glue.
According to clinical experience and animal studies, infections and impaired perfusion are the most significant causes of suture line failure. The infection-induced collagenase will increase collagen breakdown and decrease the strength of the anastomosis. Leakage may result in life-threatening peritonitis if the intestinal contents reach the free peritoneal cavity. If the suture line failure is walled off, an abscess will form, which may result in intestinal fistula>.
Abscess
The outcome of perianastomotic abscess with the risk of rupture include detritus, hematoma, foreign bodies, and lymph accumulation as well as its bacterial contamination. Deep colorectal and coloanal anastomoses are especially at risk of such infections. The presence of feces promotes infection and thus suture line failure and its sequelae.
Animal studies and clinical evidence indicate that decreased protein and plasma albumin and significant preoperative weight loss (tumor cachexia!) are risk factors in anastomosis healing.
Stenosis
Intestinal anastomoses tend to shrink.
Especially rectal anastomoses blocked from fecal transit by a colostomy become stenotic more frequently. The bougienage effect of fecal transit apparently prevents stenosis.
Wound infection
For this complication as well, the incidence depends on a wide variety of factors. The most important are: Poor immune defense of the patient (tumor cachexia, diabetes etc.), emergency surgery with a high likelihood of contamination, large bowel surgery.